This invention relates to a tuner for high power microwave circuits, and more particularly to a coaxial stub tuner which combines a fixed short circuit branch and a variable open circuit branch in a new configuration which facilitates tuning by varying the stub of the open circuit branch.
A microwave stub tuner is commonly implemented with a short circuit branch that is variable in length. The branch can, in principle, be replaced by an open circuit branch that is longer or shorter by a quarter wavelength. It is preferable to use an open circuit branch because it has less contact problems than the short circuit branch when applied to high power systems. But the open circuit branch has the problem of providing access to the stub for adjustment of its length to tune the branch.